Tools for forming grooves with circular generatrices in workpieces



4 Sheets-Sheet 1 M. ORAlN TOOLS FOR FORMING GROOVES WITH CIRCULAR GENERATRICES IN WORKPIECES 9 l 6 a w 2 9 m 2 J M. ORAIN FORMING GROOVES WITH CIRCULAR ERATRICES IN WORKPIECES Jul 29, 1969 TOOLS FOR GEN 4 Sheets-Shee'pz Filed Jan. 25, 1967 may July 29,- 1969 M. ORA 3,457,750

TOOLS FOR FORMING GROO S WITH CIRCULAR GENERATRICES IN WORKPIECES Filed Jan. 25, 1967 4 Sheets-Sheet .5

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,6 7; 75 W; mm mm July 29, 1969 M. ORAIN TOOLS' FOR FORMING GROOVES WITH CIRCULAR GENERATRICES IN WORKPIECES 4 Sheets-Sheet 4 Filed Jan. 25, 1967 MM 15V WWW/ Mm/aim United States Patent 3,457,750 TOOLS FOR FORMING GROOVES WITH CIRCU- LAR GENERATRICES IN WORKPIECES Michel (Brain, Courbevoie, France, assignor to Glacnzer Spicer, Poissy, France, a corporation of France Filed Jan. 25, 1967, Ser. No. 611,751 Claims priority, application France, Jan. 28, 1966,

Int. ci. B21!) US. Cl. 7275 30 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to tools for producing grooves having generatrices in the form of an arc of a circle in universal couplings. The tools include shaping balls carried by a support member movable by a press and guided by guide channels formed in sleeves and/or mandrels for cold forming the grooves in interior or exterior surfaces of the universal couplings.

Numerous cases exist in engineering where balls or spherical rollers are required to roll or slide in running tracks of substantially circular section. Among these cases, for example mention may be made of universal joints for transmissions and sliding splined drives.

It is known that the good operational behaviour of such joints is governed, among other essential factors, by

the exact coincidence of the profile of the running tracks a with the curvature of the balls, and above all by the ac curacy of angular and radial positioning of said running tracks. Differences in dimensions result in seizing or in excessive play, and this entails local overloading because of the hyperstatic character of these types of joints. Moreover, another disadvantage lies in the necessity to grind these running tracks in order to obtain the correct surface conditions necessary for reducing operational slippage, while in the majority of cases such grinding can be effected only with grinding wheels of very small diameters, which consequently wear out rapidly.

The tools forming the subject of the present invention is more particularly intended for machining component parts of such joints.

It is known to make grooves having sections in the form of an arc of a circle which are formed in such parts with the aid of sizing stamps, which are used for example, in the operations of stamping, extrusion or the like. In this case, however, the front portion of the parts of the punch which effect the sizing are subject to wear, and it may happen that local sizing will occur fairly quickly, thus making it impossible to produce in series accurate parts of the final dimensions.

It has also been proposed to use cutting-wheel tools for the machining of grooves, particularly those constituting the bottoms of screw threads. However, apart from the fact that such tools do not generally permit grooves to be machined which have a surface, the section of which has the shape of an arc of a circle, they have various disadvantages including rapid wear and subsequent deformation of the axles or pivots supporting the wheels, so that frequent replacement of the tools is necessary.

The present invention makes it possible to obviate the disadvantages mentioned above and supplies economical and rapid tools for machining, on the inside or on outside surface of mechanical parts, internal or external grooves having a cross-section, the contour of which is constituted by an arc of a circle, with great precision in respect of shape and relative position. The grooves obtained by means of these tools have an appearance enabling them to be used as produced, without further mechanical finishing before heat treatment, if the latter is required. The

3,457,750 Patented July 29, 1969 "ice machining effected with the tools according to the invention is very rapid in comparison with conventional machining means.

Independently of the machining of component parts of transmission joints, in all cases where grooves of circular section have to be made, the tools in question can advantageously replace breaching, because, unlike the latter, it makes it possible to produce grooves capable of forming, for example, running tracks in blind parts. In addition, the saving of time is still greater compared with machining means other than broaching, such as milling, tool boring, or grinding.

The tools forming the subject of the present invention are based on the known machining process in which, for each groove to be machined in a metal part, at least one ball is forced to penetrate into the interior or exterior surface of said part, while being held in a position in which it is able to roll, in the direction of the desired groove and to a depth which, referred to said surface, is equal to the depth of the groove which it has to machine.

This machining process has been the subject of patents relating to various special applications. Certain patents relate to the machining of plates or tubes of thin metal with a view to forming therein rectilinear, circular, or helicoidal corrugation or goffering. Other patents have described tools for forming running tracks in ball bearing cages and bushes by the strictly circular action of a belt of balls of suitable hardness. Yet others relate to devices making it possible to produce rectilinear, circular, or helicoidal grooves in the outer surface of metal bars.

None of these known devices, however, would permit the machining of parts which constitute a sliding transmission joint and which comprise a bell-shaped element and another element in the form of a ball joint intended to cooperate with the first element, into which it must be inserted and in which it must slide.

It is therefore an object of the present invention to provide tools permitting machining of this type which comprise at least one member capable of serving as support for the shaping balls when thrust is applied to the latter by the piston of a press, said balls being brought into contact with the part to be machined by guiding means, and at least one transversal retention means for the balls which surrounds said part and the balls, said means being provided in its interior with cavities holding the balls in determined angular positions in relation to the direction of the thrust, without preventing their rotation about their own axes, said positions determining the longitudinal section of the grooves formed in the part by the balls.

The member serving to support the balls and their guide means may be constituted by a mandrel provided with fins each comprising a recess having a hemispherical bottom intended to receive a shaping ball, said mandrel being capable of penetrating into a cylindrical axial bore formed in the part to be machined, around which bore there are formed crenellations disposed of in the form f a star and capable of receiving the fins of the mandrel and the balls which they contain in their individual recesses.

The member serving to support the balls may be constituted by a plate provided with hemispherical cavities engaging ball joints disposed at one of the ends of push rods, the other ends of which have a hemispherical cavity intended to bear on the shaping ball corresponding to each push rod.

The transversal retention means for the balls may be constituted by a sleeve surrounding the part to be machined and the shaping balls and in the interior of which there are formed, on the same circumference, as many spherical cavities as there are balls, said cavities being intended to receive a portion of said balls, which are then 3 held in the radial direction in order to form, in the part to be machined, rectilinear grooves parallel to the axis of said part.

The transversal retention means of the balls and the means for guiding the latter may be constituted by a sleeve surrounding the part to be machined and the shaping balls, and in the interior of which there are formed spherical grooves in the form of an arc of a circle and parallel to the axis of the part to be machined, said grooves being intended to receive a portion of said balls, the latter being held in the radial direction and guided so as to form in said part, grooves in an arc of a circle and parallel to the axis of the latter.

The transversal retention means for the balls may be constituted by two half-casings forming together a socket matching the outer shape of the part to be machined and containing on the inside spherical guide channels or grooves of the same curvature as the outside curvature of said part and cooperating with the guide means constituted by a mandrel inserted into a central cavity in the part to be machined and provided on its surface with guide channels or grooves of the same section and the same longitudinal profile in order to hold and guide the shaping balls inserted between said mandrel and said half-casings.

Examples of various embodiments of the invention and their application are described below with reference to the accompanying drawings, in which:

FIGURES 1 and 2 are two longitudinal sectional views of part of a tool according to one embodiment and intended to machine rectilinear cylindrical grooves in the two flanks of three crenellations provided in the skirt of a bell-shaped part, and illustrating the tool at the beginning and the end of the operation, respectively;

FIGURE 3 is a section along the line IIIIII in FIG- URE 2;

FIGURE 4 is a section along the line IVIV in FIG- URE 2;

FIGURES 5 and 6 illustrate in cross-section the machined part according to FIGURES 1 and 2, before penetration of the tool and after machining respectively;

FIGURES 7 and 8 are longitudinal sectional views, in two successive working positions, of a modification of the tool illustrated in FIGURES 1 to 4, for machining a similar part in which a spherical recess is additionally formed at the end of the stroke at the bottom of each crenellation;

FIGURE 9 is a section along the line IX-IX in FIG- URE 8 of the part obtained in accordance with FIG- URES 7 and 9;

FIGURE 10 is a longitudinal sectional view of a further modified embodiment for machining incurved grooves or toroidal grooves in the two respective side flanks of three crenellations formed in a spherical head having an axial bore;

FIGURES 11 and 12 are two sectional views of the head along the line XIXI in FIGURE 10, before and after machining respectively, the mandrel of the tool being shown in FIGURE 12 in section along the line XIIXII in FIGURE 10;

FIGURE 13 is a View in longitudinal section of another embodiment, for machining toroidal grooves in the interior surface of a part having a substantially spherical gravity;

FIGURE 14 is a view in section along the line XIVXIV in FIGURE 12;

"FIGURE 15 is a view in longitudinal section of a further but similar embodiment for machining toroidal grooves in the external surface of a part in the form of a spherical ring;

FIGURE 16 is a view in section along the line XVIXVI in FIGURE 15.

FIGURES 1 to 8 relate to a particular application of the invention which consists in forming running tracks in the flanks of crenellations provided in a bell-shaped part with the object of obtaining a sliding joint member in which the running tracks situated on each side of the same crenellation are intended to serve as support surfaces for the same bell-shaped member.

FIGURES 1 to 6 relate to a first embodiment of this particular application of the invention, in which the part to be machined is in the form of a bell 37 which is formed as an extension of a shaft 38 (FIGURES 1 and 2) and in which crenellations 39 having straight flanks (FIG- URE 5) have been formed, the final result to be obtained being the machining, in said flanks, of running tracks 40 (FIGURE 6) having cross-sections in the form of arcs of circles centred on the same point. In order to obtain this result, use is made of a tool according to the invention comprising two parts, namely a mandrel having a central body 41 adapted to penetrate into the cavity of the bell 37, and three fins 41a disposed at and adapted to penetrate respectively into the three crenellations 39 in said bell 37, and a sleeve 42 engaging over the fins 41a on the mandrel 41. In the bottom end of each of the fins 41a, there is formed a recess 44 having a hemispherical bottom, while a cavity 44a in the form of a segment of a sphere is formed in the interior surface of the sleeve 42 opposite each recess 44 in the mandrel, each recess 44 and the corresponding cavity 44a being arranged to receive a steel ball 43 centred to form the two tracks 40 (FIGURE 6) in the corresponding crenellation 39 when, as illustrated in FIGURES 1 and 2, the tool 41-43 is moved with the aid of a press (not illustrated) in the direction of the arrow F in relation to the part 37-38. It will of course be appreciated, that the steel balls must be made of material which is harder than the workpiece.

FIGURES 7 to 9 illustrate another embodiment of the same particular application of the invention. This embodiment contains substantially the same parts as the embodiment illustrated in FIGURES 1 to 6, these parts being designated by the same references with the addition of the prime index. Nevertheless, the recesses 44 provided in the mandrel 41 and its fins 41a are less deep, so that the balls 43' project to a greater extend towards the outside of the mandrel and can thus be driven back to penetrate at the end of the tool stroke into the bottom of the crenellations and to form at those points in the part 37 a recess 45 having a curved surface. In addition, the thrust applied to the part 37' by the balls 43 is balanced by the reaction of a die 48 which in turn is adapted to shape the conical region 49 of the part 37'.

The embodiment described so far relate to the particular application of the invention to the machining of grooves having a cross-section in the form of an arc of a circle with the aid of balls disposed in recesses having a hemispherical bottom; that is to say, said balls are held in a fixed position in relation to their support while being able to rotate freely about their own axes. The result is that the grooves formed have a centre line situated at a fixed distance from a given axis, parallel to the direction of relative movement of the tool and of the part to be machined. In other words, the centre line of each groove obtained is either a straight line parallel to that direction or a helix traced on a cylinder coaxial to said axis.

The invention nevertheless permits the machining of grooves or running tracks each of which has a centre line the distance of which from a given axis, parallel to the direction of relative displacement of the tool and Workpiece, varies along the said line, the latter being for exam ple traced on a sphere or other similar surface.

Inorder to produce such grooves, use is made of tools of the type illustrated in FIGURES 10 to 16.

In the embodiment illustrated in FIGURES 10 to 12, the part to be machined is a jaw of a homokinetic joint of the so-called tripod type, constituted by a substantially spherical head 50 which is formed at the end of a shaft 51 and in which a blind bore 52 and three crenelations 53 have previously been machined (FIGURE 11). The operation according to the invention consists in machining, in the flanks of the crenellations 53, grooves 54 having a section in the form of an arc of a circle (FIGURE 12) and the centre line 55 (FIGURE of which is itself an arc of a circle. This result is obtained by means a tool comprising guide means 56b for the balls and means for moving said balls.

The guide means 5617 consists of two half-casings 57 and 58 (FIGURE 10) forming together a cavity 59-60 matching the outer shape of the head 50, and of a mandrel 61 adapted to penetrate into the blind bore 52 in the head 50, in which it is held centred. Guide channels 62 and 63 are provided in the surface of the cavity 5960, and guide channels 64 are provided in the surface of the mandrel 61, in order to guide the three balls 56 so that their centres follow respectively the centre lines of the grooves 54 to be formed in the flanks of the crenellations 53.

The means for moving the balls consists of push-rods 65, one end of each of which is hollowed to form a bearing surface 66 in the form of a spherical segment, while the other end is shaped as a ball 67 bearing in a hemispherical recess 68 which is formed in a support plate 69 and in which said ball 67 is held by a ring 70 having an external screw thread so as to engage in a corresponding screw thread in the plate 69. The latter is fixed beneath the piston (not illustrated) of a press on the table 71 of which the bottom half-casing 58 rests.

It can easily be seen from FIGURE 10 that when the piston of the press is lowered, together with the plate 69,

the balls 56 are driven so that, being guided by the channels 62 and 63 in the half-casings 57 and 58 and by the channels 64 in the mandrel 61, they form the grooves 54 in the flanks of the crenellations 53 of the head 50. As in the previous examples, the balls 56, the half-casings 57 and 58,and the mandrel 61 are of harder steel than the head 50.

In the embodiment show in FIGURES l3 and 14, the result to be achieved is the machining of running grooves 72 in an internal cavity 73 having spherical Walls in a bell 74 of a joint of the RZEPPA type, which is forged at the end of a shaft 75. The necessary tool equipment like-wise comprises in this case guide means 76 for the balls and means of displacing the latter. Said guide means are constituted by a mandrel 77 provided with a centring point 78 which engages in a corresponding centring recess provided in the bottom of the cavity 73 of the bell 74. The mandrel 77 has a spherical swelling 79 in the external surface of which guide channels 80 are formed which are complementary to the grooves 72 to be machined, and

it is held in position by retaining means (not illustrated).

Ball displacement means are provided by push-rods 81 similar to the push-rods 65 illustrated in FIGURE 10 and each having at one end a concave spherical bearing surface 82 applied against the corresponding ball 76, and

at the other end, a spherical head 83 engaging in a corret sponding bearing surface 84 provided in a plate 85 arranged to be fixed beneath the piston of a press (not illustrated). A crown 86 resting on a press plate 87 supports and encloses the bell 74. The operation of this tool equipment is clear from FIGURE 13, without requiring a description in detail.

The example illustrated in FIGURES l5 and 16 relates to the formation of running grooves 88 in the external spherical surface of a head 89 intended to cooperate in a RZEPPA type joint with a bell, such as the bell 74 illustrated in FIGURE 13. The tool comprises an outer block 90 in the form of a ring and provided, on its interior surface with guide channels 91, and with push-rods 92 for displacing the machining balls 93, said push-rods being similar to the push-rods 81 illustrated in FIGURE 13, a plate 95 fixed beneath the piston (not illustrated) of a press acting on the spherical head 94 of said push-rods. The head 89 is placed on a support 96 fixed on a plate 97 of the press and is provided at its base with a circular flange 98 permitting the centring of the guide block 90.

Here again the operation of the tool equipment is sufficiently clear from FIGURE 15 without further description being required.

It will be understood that the embodiments described above are given solely as examples without limitation and that various other operations could be carried out in the workpieces by means of the tools according to the invention without departing from the scope of the latter. In particular, the profile, the number, and the respective position of the running tracks as illustrated in the drawings are purely illustrative. Similarly, in all the cases described the relative movement ofthe tool and of the workpiece could be obtained in the inverse manner to that described, that is to say in the embodiments illustrated in FIGURES 1 to 16 the workpiece could be displaced while the tool remains fixed. It is even possible to conceive that in the case of a helicoidal movement the tool could be displaced by axial translation and the workpiece by rotation, or vice versa.

What is claimed is:

1. A tool for producing grooves of part circular cross section having a circular generatrix in slotted workpieces comprising a support member, a shaping ball carried by said support member, said shaping ball being made of material which is harder than the workpiece, means for imparting relative movement between said support member and said workpiece to move the shaping ball along the workpiece slot to produce a groove therein, and said support member includes means guidably movable in the workpiece slot for maintaining alignment between the workpiece slot and the shaping ball to thereby control the formation of said groove.

2. The tool as defined in claim 1 wherein said support member includes a cavity housing said shaping ball.

3. The tool as defined in claim 1 including another support member movable with said first-mentioned support member into external telescopic supporting relationship to said workpiece during the formation of the grooves therein.

4. The tool as defined in claim 1 wherein said align ment maintaining means is a transversely projecting fin.

5. The tool as defined in claim 1 wherein said alignment maintaining means is a transversely projecting fin, and said fin includes a cavity housing said shaping ball.

6. The tool as defined in claim 1 wherein said support member includes a terminal end having a cavity housing said shaping ball, said cavity opens outwardly of said terminal end, and a portion of said shaping ball projects axially beyond said terminal end.

7. The tool as defined in claim 1 wherein said workpiece includes a plurality of slots, and said alignment maintaining means is defined by a plurality of transversely projecting fins each of which is received in an associated one of said slots.

8. The tool as defined in claim 4 wherein said alignment maintaining means is a transversely projecting fin.

9. The tool as defined in claim 4 wherein said workpiece includes a plurality of slots, and said alignment maintaining means is defined by a plurality of transversely projecting fins each of which is received in an associated one of said slots.

10. The tool as defined in claim 7 wherein each of said fins includes a cavity, and said first-mentioned and additional shaping balls are each individually housed in an associated one of said cavities.

11. The tool as defined in claim 10 wherein each of said balls includes a surface portion projecting axially beyond a terminal end of each of said fins.

12. A tool for producing grooves of part circular cross section having a circular generatrix in workpieces comprising a support member, a shaping ball carried by said support member, said shaping ball being made of material which is harder than the workpiece, means for imparting relative movement between said support member and said workpiece to move the shaping ball along a surface of the workpiece to produce a groove therein, and means defining a guide path along which said shaping ball is moved to thereby control the formation of said groove.

13. The tool as defined in claim 12 wherein said guide path defining means is at least partially housed within a recess of said workpiece to thereby form the groove in an interior surface portion of said workpiece.

14. The tool as defined in claim 12 .wherein said guide path defining means is disposed exteriorly of said workpiece to thereby form the groove in an exterior surface portion of said workpiece.

15. The tool as defined in claim 12 wherein the workpiece is sloted, and said guide path defining means is disposed both internallyand externally of said workpiece in a plane of said slot to thereby form the groove in the slot as the shaping ball is guided by said guide path defining means.

16. The tool as defined in claim12 wherein said support member is a push rod having opposite ends, one of said ends includes a spherical head, and said spherical head is received in a hemispherical cavity of a plate Cl (I adapted for movement toward the workpiece duringthe production of the groove therein.

17. The tool as defined in claim 12 wherein said guide path defining means in arcuate whereby the workpiece groove is formed of an arcuate nature.

18. The tool as defined in claim 13 including a mandrel disposed withinthe workpiece recess, said guide path defining means is a guide channel formed in an exterior surface of said mandrel. I

19. The tool as defined in claim 13 including a mandrel disposed within the workpiece recess said guide path defining means is a guide channel formed in an'exterior surface of said mandrel, and said support memher is a push rod which includes a terminal end having a cavity housing said shaping ball.

20. The tool as defined in claim 13 including a mandrel disposed within the workpiece recess, said guide path defining means is a guide channel formed in "an exterior surface of said mandrel, said support member is a push rod which includes a terminal end having a cavity housing said shaping ball, and said push rod includes another exteriorly surrounding said workpiece, and said guide path defining means is a guide channel formed in an interior surface of said housing.

23. The tool as defined in claim 14 including a housing exteriorly surrounding said workpiece,"saidfguidepath defining means is a guide channel formed'in an interior surface of said housing, and said support-member is a push rod which includesa terminal end having a'cavity housing said shaping'ball. I

24. The tool as defined 'in claim 14- including-'a housing exteriorly surrounding" said workpiece, "said guide path defining means is a guide channel forrned'infan interior surface of said housingfsaid support member is a push rod which includes a terminal end havingla cavity 'housing sa'id shaping ball, and said' push-rod includes another end terminating in a hemispherical head.

25. The tool as definedin c laim' 1'5 wherein said guide path defining means is a pair 'of guidechannels, one of said guide channels is disposed internally of said=workpiece and the other of said guide channels is disposed ex-.

ternally of said workpiece.

26.'-Thetool as defined in claim 15 including a mandrel disposed within theworkpiece recess and a housing exteriorly surrounding said workpiece, and said guide path defining. means is a guide channel formed in an exterior surface of said mandrel in alignment with a guide channel formed in an interior surface of said housing.

27. The tool as defined in claim 18 wherein said guide channel is arcuate whereby the workpiece groove is formed of an arcuate nature.

28. The tool as defined in claim 22 wherein said guide channel is arcuate whereby the workpiece groove is formed of an arcuate nature.

29. The tool as defined in claim 25 wherein said guide channels are arcuate whereby the workpiece groove is formed of an arcuate nature.

30. The tool as defined in claim 26 wherein said housing is formed of at least two separable portions, and

said guide channel is formed in each housing portion.

References Cited UNITED STATES PATENTS 1,596,262 8/1926 Walker 7275 1,794,797 3/1931 Rockwell 7275 1,919,869 7/1933 Stanitz et a1. 7275 2,048,598 7/1936 Christiansen 72-75 2,223,799 12/1940 Annen 72-75 CHARLES w. LA-NHAM, Primary Examiner LOWELL A. LARSON, Assistant Examiner 

